# -*- encoding: utf-8 -*-
#
# Copyright © 2013 Unitedstack Inc.
#
# Author: Jianing YANG (jianingy@unitedstack.com)
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

"""A middleware that turns exceptions into parsable string. Inspired by
Cinder's faultwrapper
"""

import traceback

from oslo.config import cfg
import webob


from heat.common import exception
from heat.common import serializers
from heat.common import wsgi
from heat.openstack.common.rpc import common as rpc_common


cfg.CONF.import_opt('debug', 'heat.openstack.common.log')


class Fault(object):

    def __init__(self, error):
        self.error = error

    @webob.dec.wsgify(RequestClass=wsgi.Request)
    def __call__(self, req):
        if req.content_type == 'application/xml':
            serializer = serializers.XMLResponseSerializer()
        else:
            serializer = serializers.JSONResponseSerializer()
        resp = webob.Response(request=req)
        default_webob_exc = webob.exc.HTTPInternalServerError()
        resp.status_code = self.error.get('code', default_webob_exc.code)
        serializer.default(resp, self.error)
        return resp


class FaultWrapper(wsgi.Middleware):
    """Replace error body with something the client can parse."""

    error_map = {
        'AttributeError': webob.exc.HTTPBadRequest,
        'ActionInProgress': webob.exc.HTTPConflict,
        'ValueError': webob.exc.HTTPBadRequest,
        'StackNotFound': webob.exc.HTTPNotFound,
        'NotFound': webob.exc.HTTPNotFound,
        'ResourceNotFound': webob.exc.HTTPNotFound,
        'ResourceTypeNotFound': webob.exc.HTTPNotFound,
        'ResourceNotAvailable': webob.exc.HTTPNotFound,
        'PhysicalResourceNotFound': webob.exc.HTTPNotFound,
        'InvalidTenant': webob.exc.HTTPForbidden,
        'Forbidden': webob.exc.HTTPForbidden,
        'StackExists': webob.exc.HTTPConflict,
        'StackValidationFailed': webob.exc.HTTPBadRequest,
        'InvalidTemplateReference': webob.exc.HTTPBadRequest,
        'InvalidTemplateVersion': webob.exc.HTTPBadRequest,
        'InvalidTemplateSection': webob.exc.HTTPBadRequest,
        'UnknownUserParameter': webob.exc.HTTPBadRequest,
        'RevertFailed': webob.exc.HTTPInternalServerError,
        'StopActionFailed': webob.exc.HTTPInternalServerError,
        'ServerBuildFailed': webob.exc.HTTPInternalServerError,
        'NotSupported': webob.exc.HTTPBadRequest,
        'MissingCredentialError': webob.exc.HTTPBadRequest,
        'UserParameterMissing': webob.exc.HTTPBadRequest,
        'RequestLimitExceeded': webob.exc.HTTPBadRequest,
        'InvalidTemplateParameter': webob.exc.HTTPBadRequest,
        'Invalid': webob.exc.HTTPBadRequest,
    }

    def _map_exception_to_error(self, class_exception):
        if class_exception == Exception:
            return webob.exc.HTTPInternalServerError

        if class_exception.__name__ not in self.error_map:
            return self._map_exception_to_error(class_exception.__base__)

        return self.error_map[class_exception.__name__]

    def _error(self, ex):

        trace = None
        webob_exc = None
        if isinstance(ex, exception.HTTPExceptionDisguise):
            # An HTTP exception was disguised so it could make it here
            # let's remove the disguise and set the original HTTP exception
            if cfg.CONF.debug:
                trace = ''.join(traceback.format_tb(ex.tb))
            ex = ex.exc
            webob_exc = ex

        ex_type = ex.__class__.__name__

        if ex_type.endswith(rpc_common._REMOTE_POSTFIX):
            ex_type = ex_type[:-len(rpc_common._REMOTE_POSTFIX)]

        full_message = unicode(ex)
        if full_message.find('\n') > -1:
            message, msg_trace = full_message.split('\n', 1)
        else:
            msg_trace = traceback.format_exc()
            message = full_message

        if cfg.CONF.debug and not trace:
            trace = msg_trace

        if not webob_exc:
            webob_exc = self._map_exception_to_error(ex.__class__)

        error = {
            'code': webob_exc.code,
            'title': webob_exc.title,
            'explanation': webob_exc.explanation,
            'error': {
                'message': message,
                'type': ex_type,
                'traceback': trace,
            }
        }

        return error

    def process_request(self, req):
        try:
            return req.get_response(self.application)
        except Exception as exc:
            return req.get_response(Fault(self._error(exc)))
